This grant application seeks funds to perform a randomized controlled trial testing the effectiveness of two guided-self-help treatments for obese patients who experience loss of control over eating (LOC) following gastric bypass surgery. The goal is to identify low-cost and easy-to-disseminate behavioral methods for improving longer-term bariatric surgery outcomes. Although bariatric surgery produces substantial weight losses and improvements in medical co-morbidities in many patients, outcome studies have found that weight regain begins to occur as early as one year postoperatively. Research has also documented improvements in eating behaviors and functioning following bariatric surgery although longer-term studies have reported considerable heterogeneity in these outcomes. Disordered eating behaviors are common following bariatric surgery. Given concerns about heterogeneity of weight loss and psychosocial outcomes following bariatric surgery, research has attempted to identify predictors of outcomes. Although disordered eating behaviors prior to surgery (and many other patient predictors) have not shown negative prognostic significance, LOC post- surgery has been found to reliably predict poorer weight loss and functioning. LOC can be reliably assessed in bariatric patients with existing methods and LOC has been shown, among obese patients, to be highly responsive to cognitive behavioral therapy (CBT) including guided self-help (gshCBT) methods that are cost- effective and can be disseminated to surgery programs. In this study, N=120 gastric bypass patients who experience LOC regularly following surgery will be randomized to one of two experimental conditions (gshCBT or gshBWL (i.e., behavioral weight loss)) or to a standard-of-care (SOC) comparison condition. Assessment of LOC and randomization to treatment will be at 6-months post-surgery. Treatments will be delivered via guided-self-help over three months by allied health clinicians to increase generalizability to bariatric surgery settings and because there exists support for their effective dissemination by non-specialist clinicians. Changes through the course of treatments will be evaluated and major outcome assessments will be conducted by independent evaluators at baseline (6 months post-surgery), post-treatment (9 months post-surgery), and at repeated follow-up assessments every six- months through 24 months after completing treatments (33 months post-surgery). Comprehensive evaluations will assess weight maintenance, LOC, eating behaviors, and associated outcomes (behavioral and psychosocial functioning). Planned analyses will test the effectiveness of gshCBT and gshBWL relative to the standard-of-care comparison condition and relative to each other for reducing LOC eating and enhancing longer-term post-surgical weight maintenance and psychosocial outcomes. Exploratory analyses will test potential predictors, moderators, and mediators of outcomes and provide estimates of cost-effectiveness.